Allocating bandwidth in a resilient packet ring network by PI controller

Abstract

Implementations and techniques for allocating bandwidth in a resilient packet ring network by a PI-type controller are generally disclosed.

1. A method implemented in a resilient packet ring network, comprising:
 measuring a current transit queue length; 
 determining a fair rate to facilitate an allocated bandwidth in the resilient packet ring network via a PI-type controller associated with at least one node of the resilient packet ring network, wherein determining the fair rate comprises determining a difference between a target queue length and the current transit queue length; and 
 stabilizing one or more transit queue lengths at the target queue length under unbalanced traffic scenarios, based at least in part on the allocated bandwidth, 
 wherein the fair rate F(n) is expressed as:
   F(n)=F(n−1)+k p (e(n)−e(n−1))+k I Te(n)
 
 
 
       where F(n−1) is a prior fair rate, where k p  is a proportional gain, where k I  is an integral gain, where e(n) is a difference between the target queue length and the current transit queue length, where e(n−1) is a prior difference between the target queue length and the current transit queue length, and where T is a sampling time between fair rate F(n) and prior fair rate F(n−1). 
     
     
       2. The method of  claim 1 , wherein determining the fair rate comprises determining a rate of change of a difference between the target queue length and the current transit queue length. 
     
     
       3. The method of  claim 1 , wherein determining the fair rate is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
     
     
       4. The method of  claim 1 , further comprising stabilizing an end-to-end delay associated with one or more transit queues under unbalanced traffic scenarios, based at least in part on the allocated bandwidth. 
     
     
       5. The method of  claim 1 , wherein the proportional gain k p  is expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 p 
               
               < 
               
                 1 
                 
                   W 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   τ 
                 
               
             
           
         
       
       where W is a sum of weights associated with nodes of the resilient packet ring network and where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
     
     
       6. The method of  claim 1 , wherein the integral gain k I  is expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 I 
               
               < 
               
                 
                   k 
                   p 
                 
                 τ 
               
             
           
         
         where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
       
     
     
       7. The method of  claim 1 , wherein the proportional gain k p  is expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 p 
               
               < 
               
                 1 
                 
                   W 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   τ 
                 
               
             
           
         
       
       where W is a sum of weights associated with nodes of the resilient packet ring network and where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network; and
 wherein the integral gain k I  is expressed as: 
 
       
         
           
             
               0 
               < 
               
                 k 
                 I 
               
               < 
               
                 
                   
                     k 
                     p 
                   
                   τ 
                 
                 . 
               
             
           
         
       
     
     
       8. An article for use with a resilient packet network, comprising:
 a non-transitory signal bearing medium comprising machine-readable instructions stored thereon, which, if executed by one or more processors, operatively enable a computing device to: 
 measure a current transit queue length; 
 determine a fair rate to facilitate an allocated bandwidth in the resilient packet ring network via a PI-type controller associated with at least one node of the resilient packet ring network, wherein the determination of the fair rate comprises determining a difference between a target queue length and the current transit queue length; and 
 stabilize one or more transit queue lengths at the target queue length under unbalanced traffic scenarios, based at least in part on the allocated bandwidth, 
 wherein the fair rate F(n) is expressed as:
   F(n)=F(n−1)+k p (e(n)−e(n−1))+k I Te(n)
 
 
 where F(n−1) is a prior fair rate, where k p  is a proportional gain, where k I  is an integral gain, where e(n) is a difference between the target queue length and the current transit queue length, where e(n−1) is a prior difference between the target queue length and the current transit queue length, and where T is a sampling time between fair rate F(n) and prior fair rate F(n−1). 
 
     
     
       9. The article of  claim 8 , wherein the determination of the fair rate is based at least in part on rate of change of a difference between the target queue length and the current transit queue length. 
     
     
       10. The article of  claim 8 , wherein the determination of the fair rate is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
     
     
       11. The article of  claim 8 , further comprising stabilizing an end-to-end delay associated with one or more transit queues under unbalanced traffic scenarios, based at least in part on the allocated bandwidth. 
     
     
       12. The article of  claim 8 , wherein the determination of the fair rate is based at least in part on the proportional gain k p  expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 p 
               
               < 
               
                 1 
                 
                   W 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   τ 
                 
               
             
           
         
       
       where W is a sum of weights associated with nodes of the resilient packet ring network and where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
     
     
       13. The article of  claim 8 , wherein the determination of the fair rate is based at least in part on the integral gain k I  expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 I 
               
               < 
               
                 
                   k 
                   p 
                 
                 τ 
               
             
           
         
         where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
       
     
     
       14. A resilient packet ring network, comprising:
 a plurality of nodes; 
 an inner ring of links associated between the plurality of nodes; 
 an outer ring of links associated between the plurality of nodes; and 
 a PI-type controller associated with at least one of the plurality of nodes, wherein the PI-type controller is configured to:
 measure a current transit queue length; 
 determine a fair rate to facilitate an allocated bandwidth in the resilient packet ring network, wherein the determination of the fair rate comprises determining a difference between a target queue length and the current transit queue length, and 
 stabilize one or more transit queue lengths at the target queue length under unbalanced traffic scenarios, based at least in part on the allocated bandwidth, 
 wherein the fair rate F(n) is expressed as:
   F(n)=F(n−1)+k p (e(n)−e(n−1))+k I Te(n)
 
 
 
 where F(n−1) is a prior fair rate, where k p  is a proportional gain, where k I  is an integral gain, where e(n) is a difference between the target queue length and the current transit queue length, where e(n−1) is a prior difference between the target queue length and the current transit queue length, and where T is a sampling time between fair rate F(n) and prior fair rate F(n−1). 
 
     
     
       15. The resilient packet ring network of  claim 14 , wherein the determination of the fair rate is based at least in part on the proportional gain k p  expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 p 
               
               < 
               
                 1 
                 
                   W 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   τ 
                 
               
             
           
         
       
       where W is a sum of weights associated with nodes of the resilient packet ring network and where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
     
     
       16. The resilient packet ring network of  claim 14 , wherein the determination of the fair rate is based at least in part on the integral gain k I  expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 I 
               
               < 
               
                 
                   k 
                   p 
                 
                 τ 
               
             
           
         
         where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
       
     
     
       17. An apparatus for use with a resilient packet network, comprising:
 a PI-type controller associated with at least one of a plurality of nodes in the resilient packet ring network, wherein the PI-type controller is configured to:
 measure a current transit queue length; 
 determine a fair rate to facilitate an allocated bandwidth in the resilient packet ring network, wherein the determination of the fair rate comprises determining a difference between a target queue length and the current transit queue length; and 
 stabilize one or more transit queue lengths at the target queue length under unbalanced traffic scenarios, based at least in part on the allocated bandwidth, 
 wherein the fair rate F(n) is expressed as:
   F(n)=F(n−1)+k p (e(n)−e(n−1))+k I Te(n)
 
 
 
 where F(n−1) is a prior fair rate, where k p  is a proportional gain, where k I  is an integral gain, where e(n) is a difference between the target queue length and the current transit queue length, where e(n−1) is a prior difference between the target queue length and the current transit queue length, and where T is a sampling time between fair rate F(n) and prior fair rate F(n−1). 
 
     
     
       18. The apparatus of  claim 17 , wherein the PI-type controller is further configured to determine the fair rate based at least in part on the proportional gain k p  expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 p 
               
               < 
               
                 1 
                 
                   W 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   τ 
                 
               
             
           
         
       
       where W is a sum of weights associated with nodes of the resilient packet ring network and where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network. 
     
     
       19. The apparatus of  claim 17 , wherein the PI-type controller is further configured to determine the fair rate based at least in part on the integral gain k I  expressed as: 
       
         
           
             
               0 
               < 
               
                 k 
                 I 
               
               < 
               
                 
                   k 
                   p 
                 
                 τ 
               
             
           
         
         where τ is based at least in part on a round trip delay between a bottleneck link of the resilient packet ring network and the at least one node of the resilient packet ring network.